1. Field of the Invention
The present invention relates to a liquid crystal display device.
2. Description of the Related Art
Liquid crystal display devices have been widely used as display devices of information communication terminals such as computers, or television receivers. The liquid crystal display device is a device to display an image by changing the alignment of a liquid crystal composition sealed between two substrates with a change in electric field, and controlling the degree of transmission of light passing through the two substrates and the liquid crystal composition. In order to change the electric field, a voltage corresponding to the gray-scale value of each of pixels is applied to a pixel electrode via a pixel transistor of each of the pixels.
In a so-called in-plane switching (IPS) type liquid crystal display device in which the pixel electrode and a counter electrode that forms the electric field in combination with the pixel electrode are formed in the same thin film transistor (TFT) substrate, white display is changed into blue one or yellow one depending on viewing angle directions, and thus image quality is reduced in some cases. It has been known for solving this image quality reduction to use a dual-domain structure in which two areas (domains) where electrodes extend in different directions are formed in each of the pixels to vary the alignment state of the liquid crystal composition, and thus the changes in color are canceled out each other Japanese Patent No. 4414824 discloses a liquid crystal display device in which a pixel is divided into four domains to thereby improve viewing angle characteristics.
In the dual-domain structure described above, since the liquid crystal composition is not operated at a portion at which the direction of the electrode changes and the portion is not used as the effective area of the pixel, there is a risk of a reduction in transmittance.